The present invention relates to an apparatus for fitting a stabilizer to a vehicle, particularly to a passenger car.
A passenger car is generally equipped with a stabilizer applied to a pair of front wheels. The stabilizer consists of a U-shaped torsion bar, the opposite ends of which are so connected to the right and left wheels that the torsional resistance of the bar relieves the car from an inclination to one side due to the centrifugal force, while the car turns. Most modern vehicles are designed to be equipped with an independent suspension system for the front wheels, in which each wheel behaves independently from and is unaffected by the other wheel for the purpose of suppressing rolling when traveling straight. High speed operation requires a stabilizer assembly with a stronger torsion bar, but then operation of the supension on one side influences the suspension on the other, leading to considerable disadvantages. One of the disadvantages is that in the case where a wheel passes over a hole in a road when traveling straight, a stronger torsion bar would prevent a wheel from dropping completely into the hole, producing as consequence poor road-holding performance. In this situation, the vehicle would roll more than if a weaker or no torsion bar were fitted. Another disadvantage is that, when the vehicle travels straight, a relatively large bump would induce more roll than were no stabilizer fitted, because the stabilizer and the suspension spring overlap each other to bring an excessively strong action. Furthermore, a shock absorber is required to have a strong braking force sufficient to equal the sum of the spring constants of the respective torsion bar and suspension spring, leading to a further disadvantage that move vibrations under spring are transmitted the frame of the vehicle creating an uncomfortable ride. When one wheel passes over a raised place, the other has the road-holding lowered by the torsional resistance in the stabilizer, resulting in a poor straight-running performance.
The apparatus known by my U.S. Pat. No. 4,066,278 and British Pat. No. 1,514,378 is one that comprises a friction damper assembly of the type having a preselected braking force with a predetermined stroke. The apparatus has been arranged to absorb the initial distorsion of the stabilizer of torsion bar so as to give the vehicle a good straight-running performance and a comfortable ride without diminishing the anti-roll rigidity of the vehicle. That is, without diminishing the resistibility against inclination to one side due to the centrifugal force produced during the turning of the vehicle or the resistibility against side wind. However, the friction damper remains unmoved when a wheel passes over a relatively small bump, because of having the maximum braking force when it commences sliding from the neutral position. Accordingly, the friction damper maintains no better comfort than when the vehicle travels on a good road. The friction damper produces a so-called stick-slip accompanying uncomfortable shock and noise in the starting of movement. The friction damper has a resisting force that is characteristically shown by a flat line without increasing toward the end of stroke and substantially identical in the both advance and return processes. This is the reason why the piston sometimes fails to reach the neutral position and stops at a position slightly before the position in the return process, resulting in the fact that the vehicle is caused to roll when the wheel behaves rapidly.
Stabilizer fitting apparatus, such as the friction damper, must be contained within the recess of a tire together with other parts, such as a brake hose, a brake drum, a lower arm and the like, in order to protect themselves from making a contact with a steering wheel. However, the apparatus as described above is disadvantageously too large to be contained in a restricted space in a small size passenger car.
It is an object of the present invention to provide a stabilizer assembly free from the disadvantages of the prior art.
This and other objects and advantages of the invention may be readily ascertained by referring to the following description and appended drawings.
In accordance with the invention, the stabilizer assembly is capable of nullification of the stabilizer-action while in straight-line traveling and equipped with means for resolving the instability produced by the nullification of the stabilizer-action while turning. The means has a resisting force that gradually increases when it is in the advance process from the neutral position to the end of the stroke and is substantially naught when it is in the return process from the end of the stroke to the neutral position.